Vulnerability-Lookup

GHSA-MQ36-523M-X7VV

Vulnerability from github – Published: 2026-08-20 18:35 – Updated: 2026-08-20 18:35

Summary

node-opcua missing nonce verification in UserNameIdentityToken authentication

Details

Summary A missing nonce verification in the UserNameIdentityToken authentication handler allows an unauthenticated remote attacker to forge a password token that extracts as an empty string, and to replay captured authentication tokens across sessions.

Affected versions: <= 2.165.0 Tested version: 2.165.0 CVSS Score: 8.1 (High) CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L CWE: CWE-347 Improper Verification of Cryptographic Signature

Root Cause

In packages/node-opcua-server/source/opcua_server.ts at line 1886-1887, after RSA-OAEP decrypting the UserNameIdentityToken password blob, the server reads a 4-byte little-endian length field and extracts buff[4 : 4+length] as the password. It never verifies that the trailing bytes equal session.nonce.

This has two consequences:

Forged empty password: An attacker who retrieves the server's public key via an unauthenticated GetEndpoints call can craft a token where the 4-byte length field equals serverNonce.length (32). The server computes length = 32 - 32 = 0 and calls isValidUser(username, ""). Any account that accepts an empty password is compromised.
Unconditional replay attack: Because nonce binding is structurally absent, any captured UserNameIdentityToken ciphertext can be replayed in a different session unconditionally.

The impact is compounded by a second issue: when the channel uses SecurityMode=None, verifyClientSignature returns true unconditionally (security_policy.ts:697-700), bypassing the channel-level signature check entirely.

Proof of Concept (logic, no exploit code)

1. GetEndpoints (unauthenticated) → retrieve server public key and RSA token policy
2. OpenSecureChannel (SecurityMode=None)
3. CreateSession
4. Craft plaintext: [0x20, 0x00, 0x00, 0x00]  (readUInt32LE = 32 = serverNonce.length)
5. RSA-OAEP encrypt with server public key → 256-byte ciphertext
6. ActivateSession with crafted UserNameIdentityToken
7. Server decrypts → length = 32 - 32 = 0 → password = ""
8. isValidUser(username, "") is called

Dynamically confirmed: decryption produces password = "" with no error and no nonce verification.

Suggested Fix

After decrypting the password blob, verify that buff.slice(4 + passwordLength) equals session.nonce before extracting the password. Reject the token if verification fails.

I am following a 90-day responsible disclosure policy. I am happy to provide additional technical details under embargo. Please confirm receipt at your earliest convenience.

Reporter: Stanley Tobias Discovery date: 2026-03-23

Severity

7.7 (High)


                  
                    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L

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JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "node-opcua"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "2.165.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-54155"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-347"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-20T18:35:33Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "**Summary**\nA missing nonce verification in the UserNameIdentityToken authentication handler allows an unauthenticated remote attacker to forge a password token that extracts as an empty string, and to replay captured authentication tokens across sessions.\n\n**Affected versions:** \u003c= 2.165.0\n**Tested version:** 2.165.0\n**CVSS Score:** 8.1 (High)\n**CVSS Vector:** CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L\n**CWE:** CWE-347 Improper Verification of Cryptographic Signature\n\n---\n\n**Root Cause**\n\nIn `packages/node-opcua-server/source/opcua_server.ts` at line 1886-1887, after RSA-OAEP decrypting the UserNameIdentityToken password blob, the server reads a 4-byte little-endian length field and extracts `buff[4 : 4+length]` as the password. It never verifies that the trailing bytes equal `session.nonce`.\n\nThis has two consequences:\n\n1. **Forged empty password:** An attacker who retrieves the server\u0027s public key via an unauthenticated `GetEndpoints` call can craft a token where the 4-byte length field equals `serverNonce.length` (32). The server computes `length = 32 - 32 = 0` and calls `isValidUser(username, \"\")`. Any account that accepts an empty password is compromised.\n\n2. **Unconditional replay attack:** Because nonce binding is structurally absent, any captured UserNameIdentityToken ciphertext can be replayed in a different session unconditionally.\n\nThe impact is compounded by a second issue: when the channel uses `SecurityMode=None`, `verifyClientSignature` returns `true` unconditionally (security_policy.ts:697-700), bypassing the channel-level signature check entirely.\n\n---\n\n**Proof of Concept (logic, no exploit code)**\n\n```\n1. GetEndpoints (unauthenticated) \u2192 retrieve server public key and RSA token policy\n2. OpenSecureChannel (SecurityMode=None)\n3. CreateSession\n4. Craft plaintext: [0x20, 0x00, 0x00, 0x00]  (readUInt32LE = 32 = serverNonce.length)\n5. RSA-OAEP encrypt with server public key \u2192 256-byte ciphertext\n6. ActivateSession with crafted UserNameIdentityToken\n7. Server decrypts \u2192 length = 32 - 32 = 0 \u2192 password = \"\"\n8. isValidUser(username, \"\") is called\n```\n\nDynamically confirmed: decryption produces `password = \"\"` with no error and no nonce verification.\n\n---\n\n**Suggested Fix**\n\nAfter decrypting the password blob, verify that `buff.slice(4 + passwordLength)` equals `session.nonce` before extracting the password. Reject the token if verification fails.\n\n---\n\nI am following a 90-day responsible disclosure policy. I am happy to provide additional technical details under embargo. Please confirm receipt at your earliest convenience.\n\nReporter: Stanley Tobias\nDiscovery date: 2026-03-23",
  "id": "GHSA-mq36-523m-x7vv",
  "modified": "2026-08-20T18:35:33Z",
  "published": "2026-08-20T18:35:33Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/node-opcua/node-opcua/security/advisories/GHSA-mq36-523m-x7vv"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/node-opcua/node-opcua"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "node-opcua missing nonce verification in UserNameIdentityToken authentication"
}

CVE-2026-54155 (GCVE-0-2026-54155)

Vulnerability from cvelistv5 – Published: 2026-09-14 16:07 – Updated: 2026-09-14 16:39

Title

node-opcua: Missing nonce verification in UserNameIdentityToken authentication

Summary

node-opcua is an OPC UA implementation for TypeScript and Node.js. Prior to 2.166.0, the UserNameIdentityToken authentication handler in packages/node-opcua-server/source/opcua_server.ts decrypts an RSA-OAEP password blob but does not verify that the trailing bytes match the current session serverNonce. An unauthenticated remote attacker can obtain the server public key through GetEndpoints and forge a blob whose little-endian length produces an empty password passed to isValidUser, compromising accounts that accept an empty password. Missing nonce binding also allows a captured UserNameIdentityToken ciphertext to be replayed in another session, and SecurityMode=None removes the separate client-signature safeguard. This issue is fixed in version 2.166.0.

Severity

7.7 (High)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-14 16:39 UTC

CWE

CWE-347 - Improper Verification of Cryptographic Signature

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/node-opcua/node-opcua/security…	x_refsource_CONFIRM
https://github.com/node-opcua/node-opcua/commit/c…	x_refsource_MISC
https://github.com/node-opcua/node-opcua/releases…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
node-opcua	node-opcua	Affected: < 2.166.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
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        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-54155",
                "options": [
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                    "Exploitation": "none"
                  },
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                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
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                "role": "CISA Coordinator",
                "timestamp": "2026-09-14T16:39:00.556555Z",
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        }
      ],
      "metrics": [
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          "cvssV3_1": {
            "attackComplexity": "HIGH",
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            "availabilityImpact": "LOW",
            "baseScore": 7.7,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
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Sightings

Author	Source	Type	Date	Other

Nomenclature

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Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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